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  • Articles  (3)
  • Amazonia  (1)
  • Baculovirus  (1)
  • Brachiaria humidicola  (1)
  • Springer  (3)
  • Wiley-Blackwell
  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (3)
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  • Articles  (3)
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  • Springer  (3)
  • Wiley-Blackwell
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  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (3)
  • Biology  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Integrated Soybean Pest Management in Micro River Basins in Brazil (2000)
    Springer
    Integrated pest management reviews 5 (2000), S. 75-80 
    Details
    ISSN: 1572-9745
    Keywords: integrated pest management ; soybean ; micro river basin ; pests ; Trissolcus basalis ; Baculovirus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A Soybean IPM system was deployed in large, continuous river basin areas. The system was designed to improve the productivity of the rural environment by restoring balance among pests and their natural enemies. The system was developed with the active participation of various governmental, industrial and academic institutions, and it was based on the main approaches utilized by the EMBRAPA soybean IPM program referred here as IPM-Soybean. The work of IPM-Soybean in microbasins is being implemented in five counties in Paraná state (Campo Mourão, Mamborê, Missal, Cambé and Toledo) in an area of approximately 18,020 ha of soybean involving 343 producers at various stages of implementation. The results obtained in the Rio do Campo basin in Campo Mourão, after four years of IPM-Soybean, showed drastic changes in pest control practices. Mean number of insecticide applications per cropping year in the river basin fell from 2.8 (1993/94 season) to 1.23 four seasons later. Biological control of the velvetbean caterpillar, Anticarsia gemmatalis, by Baculovirus anticarsia increased 57%, from 205 ha treated with this biological product in the 1993/94 season to 2730 ha in 1998. A mean of about 300,000 Trissolcus basalis (Wollaston) adults were released per year to control soybean stink bugs. As a consequence of the parasitoid release and the use of more selective insecticides, the number of insecticide applications to control stink bugs was significantly reduced. After two soybean seasons with IPM-Soybean in the river basin, mean applications for stink bugs decreased from 0.81 before the program started to 0.09 in 1996. The mean number of applications in the region and the state respectively were 9.20 and 11.44 times greater. In 1997 and 1998, the results again showed very low population densities of stink bugs in the river basin area, with a consequent reduction in insecticide applications for the control of these pests. Furthermore there was a substantial improvement in the range of products used in this area for soybean pest control. Broad spectrum products, used in 97.5% of the applications before start of IPM-Soybean (1993/94), were replaced with more selective products, especially biologicals and growth regulators. The latter had rarely been used by the river basin producers before the study (0.6% of the applications), but they accounted for 35.8% of the applications after four seasons with IPM-Soybean. IPM-Soybean developed in river basins has resulted in a more stable control system that, in turn, provides greater long-term equilibrium between the pests and the natural enemies populations in these soybean producing areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009653717787
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  • 2
    Electronic Resource
    Electronic Resource
    Nitrogen use in mixed tree crop plantations with a legume cover crop (2000)
    Springer
    Plant and soil 225 (2000), S. 63-72 
    Details
    ISSN: 1573-5036
    Keywords: agroforestry ; Amazonia ; Bactris gasipaes ; humid tropics ; Pueraria phaseoloides ; root activity ; Theobroma grandiflorum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a multi-strata agroforestry system in central Amazonia, we studied the nitrogen (N) use of two indigenous fruit tree species, Theobroma grandiflorum Willd. (ex Spreng.) K. Schum. (cupuaçu) and Bactris gasipaes Kunth. (peachpalm) for heart of palm production, and a legume cover crop, Pueraria phaseoloides Roxb. (Benth.) (pueraria). 15N was applied at a rate of 1 kg ha−1 twice at the beginning and at the peak of the rainy season, in a split plot design under either cupuaçu, peachpalm or pueraria together with fertilizer N usually applied (95.4 and 42.4 g N tree−1 for cupuaçu and peachpalm, respectively). Plant and soil 15N content and total 15N uptake were measured for 1 year. The highest N uptake by the trees occurred from areas underneath their canopy being more than 70% of their total N uptake. During the dry season, pueraria also took up most of its N (more than 70%) from the area underneath its own canopy. During the rainy season, however, pueraria utilized N from the area under cupuaçu (27–40%) and peachpalm (34–47% of the total N uptake by pueraria). Cupuaçu took up between 12 and 26% of its N from the area covered by pueraria, peachpalm slightly less with 10 to 18% (significant only at the end of the rainy season; P〈0.05). Competition for N uptake between the trees was negligible. The above-ground recovery was highest in cupuaçu (15% of the applied 15N), followed by pueraria (11%) and peachpalm (3%). Pueraria proved to be very important for the N cycling in the mixed tree cropping system recovering most (31%) of the applied 15N in plant and soil in comparison to cupuaçu (20%) and peachpalm (21%). However, the natural 15N abundance of the tree leaves did not show a significant transfer of biologically fixed N2 from pueraria to the trees (P〉0.05) and the cover crop did not improve tree N nutrition. The investigated fruit trees did not benefit from biologically fixed N2 of the legume cover crop due to their low lateral root activity and the high available soil N contents largely being an effect of the amount and placement of mineral fertilizer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026580127965
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  • 3
    Electronic Resource
    Electronic Resource
    Litter deposition and disappearance in Brachiaria pastures in the Atlantic forest region of the South of Bahia, Brazil (1999)
    Springer
    Nutrient cycling in agroecosystems 54 (1999), S. 99-112 
    Details
    ISSN: 1573-0867
    Keywords: animal stocking rate ; Brachiaria humidicola ; Desmodium ovalifolium ; litter dynamics ; humid tropics ; net aerial primary production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Over the last 25 years more than 70 million ha of the native vegetation in Brazil have been replaced by pastures for beef production planted to grasses of the genus Brachiaria, and to a lesser extent Andropogon gayanus, both of African origin. Some years after implantation, these pastures decline in productivity, probably due to low availability of P, and immobilisation of N in the soil due to the large quantities of senescent leaves (litter) of high C:N ratio deposited on the soil surface. In this paper we report the effects of the introduction of a forage legume (Desmodium ovalifolium) and different animal stocking rates on the deposition and decomposition of plant litter in pastures of Brachiaria humidicola at a site in the coastal Atlantic forest region of the south of Bahia State (Brazil). Litter existing on the ground, and that deposited in 14-day periods, was monitored at monthly intervals during 3 years of the study. Doubling the stocking rate from 2 to 4 animals ha-1 caused a highly significant decrease in litter deposition, but the presence of the legume in the sward had little effect. Calculations made directly from the quantities of litter deposited in the 14-day periods showed that between 15 and 18 tons of litter dry matter (dm) were deposited annually, but the relatively small quantities of existing litter (annual means of 0.8 to 1.5 t dm ha-1), showed that decomposition was rapid, showing values for half life of between 22 and 33 days. This technique was assumed to underestimate true litter disappearance rates, as with such rapid decomposition a significant proportion of the litter disappeared within the 14-day collection periods. An equation was developed to correct for this loss of litter during the collection periods and corrected litter decomposition constants of 0.037 to 0.097 g g-1 day-1 were recorded resulting in half lives of between 9 and 20 days. Using these data and adding them to estimates of animal consumption the net aerial primary productivity (NAPP) of the pastures ranged from 28 to 34 t dry matter ha-1 yr-1. Experiments with litter bags, and a "covered litter" system which allowed access of soil fauna to the litter, indicated that soil faunal activity had little impact on litter disappearance and such techniques underestimated true litter decomposition by at least an order of magnitude. We suggest that this underestimation is due to the fact, that in contrast to litter bags, in the open field situation fresh litter is being added continuously. As this material consists of both easily degradable ("active") and recalcitrant fractions, the easily degradable fraction fuels an active microbial biomass which continuously degrades the less decomposable material. It is concluded that the approach used in this study gives more realistic, and much higher estimates, of net primary aerial production of tropical grasslands and pastures than techniques heretofore utilised.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009797419216
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